<add key="ClientValidationEnabled" value="true" />
 <add key="UnobtrusiveJavaScriptEnabled" value="true" />

   [DataType(DataType.Text)]
        [StringLength(10, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 10)]
        [LocalizedDisplayName("EDRPOU", NameResourceType = typeof(Payerstring))]
        public string EDRPOY { get; set; }

@using (Html.BeginForm("Add", "Payer", FormMethod.Post,new { @id = "form_Add_Payer_Content" }))
{
    Html.EnableClientValidation(true);

...

  @Html.TextBoxFor(model => model.EDRPOY, new { @id = "EDRPOY", @class = "payer_search", placeholder = Payerstring.EDRPOU_Name, maxlength = 10, @style = "width:auto%" })
                     @Html.ValidationMessageFor(model => model.EDRPOY)

$(document).ready(function () {
   
    $(document.body).on('blur', '#form_Add_Payer_Content', function ()
    {    
        $(this).valid();
        
    });
});