I think you might have misunderstood, or I did not explain properly :) .
I meant that you should change your SP to something like
create procedure search (@text varchar(50))
as
select *from employees where
cast(id as varchar)=cast(@text as varchar) or
cast(age as varchar)=cast(@text as varchar) or
cast(name as varchar)=cast(@text as varchar) or
date = CAST(@text AS datetime))
As I said before, I am not an proficient in SQL, so the option I have shown for the date comparison may not be correct for your data. It may be that one of the
SELECT convert(datetime,@text,4)
would be a better fit.