client_id | name | phone | e-mail 
1         | Иван |       | i@iv.ru
2         |      | 99999 |
3         | Иван |       | i@iv.ru
4         |      | 99999 | i@iv.ru
5       | Андрей |       | i@iv.ru
7       |  Денис |       | 
8       |        | 8888  | b@iv.ru
9       |        | 9999  | c@iv.ru

create table myTable (
[data] varchar(max)
);

insert into myTable ('1         | Иван |       | i@iv.ru');
insert into myTable ('2         | Иван |       | i@iv.ru');
insert into myTable ('3         | Иван |       | i@iv.ru'); 
blablabla

declare @t table (
       [client_id] int,
       [name] varchar(255),
       [phone] varchar(50),
       [mail] varchar(50)
);

insert into @t values (1, 'NAME1', 'PHONE1', NULL);
insert into @t values (2, 'NAME2', 'PHONE2', NULL);
insert into @t values (3, 'NAME3', NULL,     'EMAIL3');
insert into @t values (4, 'NAME4', NULL,     'EMAIL4');
insert into @t values (5, NULL,    'PHONE1', 'EMAIL1');
insert into @t values (6, NULL,    'PHONE2', 'EMAIL2');
insert into @t values (7, 'NAME5',    'PHONE3', NULL);
insert into @t values (8, NULL,    'PHONE3', 'EMAIL5');


with clients as (
    select [client_id], [name], [phone], [mail] from @t where [name] is not null
)
select
      clients.[client_id],
      clients.[name],
      coalesce(clients.[phone], c1.[phone], c2.[phone]) as [phone],
      coalesce(clients.[mail], c1.[mail], c2.[phone]) as [mail]
from clients
    outer apply (select top(1) [client_id], [phone], [mail] from @t t where t.[client_id] > clients.[client_id] and t.[phone] = clients.[phone]) c1
    outer apply (select top(1) [client_id], [phone], [mail] from @t t where t.[client_id] > clients.[client_id] and t.[mail] = clients.[mail]) c2

declare @t table (
       [client_id] int,
       [name] varchar(255),
       [surname] varchar(255),
       [sex] char,
       [birthday] date,
       [phone] int,
       [amount] int
);

insert into @t values (1, 'Иван',   'Иванов', 'м',  '01.01.72',  null,  null)      
insert into @t values (2, 'Ольга',  null,     'ж',  '02.03.90',  22222, 500)
insert into @t values (3, 'Иван',   null,     null, '01.01.72',  11111, 600)
insert into @t values (4, 'Денис',  null,     'м',  '03.03.80',  33333, 400)
insert into @t values (5, 'Андрей', null,     'м',  '01.01.72',  null,  null)
insert into @t values (7, 'Денис',  null,     null, null,        33333, 400)
insert into @t values (8, 'Ольга',  'Олевна', 'ж',  '02.03.90',  22222, 500)
insert into @t values (9, 'Иван',   'Иванов', 'м',  null,        11111, 600);

with clients as (
    select
          count(1) over (partition by isnull([phone], cast(newid() as varbinary(6))), [amount] order by [client_id] range between unbounded preceding and unbounded following) as [xcnt], 
          sum(1) over (partition by isnull([phone], cast(newid() as varbinary(6))), [amount] order by [client_id]) as [xrn],
          *
    from @t
)
select [client_id], [name], [surname], [sex], [birthday], [phone], [amount] from clients where [xcnt] = 1
union
select
      c1.[client_id],
      coalesce(c1.[name], cx.[name]) as [name],
      coalesce(c1.[surname], cx.[surname]) as [surname],
      coalesce(c1.[sex], cx.[sex]) as [sex],
      coalesce(c1.[birthday], cx.[birthday]) as [birthday],
      c1.[phone],
      c1.[amount]
from clients c1
    outer apply (
         select
               max(c2.[name]) as [name],
               max(c2.[surname]) as [surname],
               max(c2.[sex]) as [sex],
               max(c2.[birthday]) as [birthday]
         from clients c2  
         where c2.[phone] = c1.[phone]
           and c2.[amount] = c1.[amount]
           and c2.[xcnt] > 1
           and c2.[xrn] > 1
    ) cx
where c1.[xcnt] > 1
  and c1.[xrn] = 1
order by client_id