Validate request

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1. if tax_id is not null and age>=14
   1. search fields: tax_id, first_name, last_name, birthbirth_date
   2. additional fields: second_name, phone_number
2. if tax_id is null and age>=14
   
   1. search fields: first_name, last_name, birth_date
   2. additional fields: tax_id, second_name, phone_number
3. if age<14
   
   1. search fields: birth_certificate, birth_date
   2. additional fields:  first_name, last_name, second_name

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