You can concatenate fields of a table to look in both fields (as well any of them):
select * from friend_reg_user where 1=1
and concat(fname,' ', lname) like '%$search%' and status='Active'
Still if user will make a 'typo' inserting two spaces between first and last name, this query won't work.
An alternative would be to split search string with a space and look for individual words (using a clever mixture of AND and OR 😉 )