It's quite possible that it's the content of your TextBoxes that gives the problem: SQL LIKE doesn't work the same as Windows "*.*" file wildcards.
Try adding a leading and trailing "%":
... OR StudentFirstName LIKE '%" + stud_search.Text + "%' OR ...
and it may start to do what you want.
But seriously, as RyanDev says, never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead, even for testing - it's a lot safer (and generally easier to read as well).
If you don't do it to start with, you won;t come back later and fix it - and it will bite you very badly later when your DB gets damaged by accident...and you don't know how it happened.