Your 4 (count them: four) user inputs can be tested for duplicate combinations just by one query:
select * from mytable where
name = <name>
or surname = <surname>
or DoB = <dob>
or Nationality = <nationality>
If you want to test for combinations with at least two factors, use
select * from mytable where
(name = <name> and surname = <surname>)
or (name = <name> and DoB = <dob>)
or (name = <name> and Nationality = <nationality>)
or (surname = <surname and DoB = <dob>)
...