SQL> select  banner
  2    from  v$version
  3  /

BANNER
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production
CORE    12.1.0.2.0      Production
TNS for 64-bit Windows: Version 12.1.0.2.0 - Production
NLSRTL Version 12.1.0.2.0 - Production

SQL> create table json_data(id number, js clob)
  2  /

Table created.

SQL> insert into json_data values(1, '{"values":"RS_485"}')
  2  /

1 row created.

SQL> CREATE INDEX json_docs_search_idx ON json_data(js)
  2    INDEXTYPE IS CTXSYS.CONTEXT
  3    PARAMETERS ('section group CTXSYS.JSON_SECTION_GROUP SYNC (ON COMMIT)')
  4  /

Index created.

SQL> select *
  2  from json_data
  3  where JSON_TEXTCONTAINS(js, '$.values', 'RS_485')  
  4  /

        ID JS
---------- --------------------------------------------------------------------------------
         1 {"values":"RS_485"}

SQL> select *
  2  from json_data
  3  where JSON_TEXTCONTAINS(js, '$.values', 'RS')
  4        and JSON_TEXTCONTAINS(js, '$.values', '485')  
  5  /

        ID JS
---------- --------------------------------------------------------------------------------
         1 {"values":"RS_485"}

SQL> 

SQL> set long 10000
SQL> variable c clob
SQL> begin
  2      dbms_utility.expand_sql_text(Q'[select *
  3  from json_data
  4  where JSON_TEXTCONTAINS(js, '$.values', 'RS_485')]',:c);
  5  end;
  6  /

PL/SQL procedure successfully completed.

SQL> print c

C
--------------------------------------------------------------------------------
SELECT "A1"."ID" "ID","A1"."JS" "JS" FROM "SCOTT"."JSON_DATA" "A1" WHERE "CTXSYS
"."CONTAINS"("A1"."JS",'{RS_485} INPATH(/values)')>0

SQL>