Using LIKE or Full-text when searching database
Having a wildcard in front of your search term will prevent SQL Server from being able to use an index and thus become painful very fast. 2 things you could do, besides going for full text search:


The obvisous one, do not put a wildcard at the start of the keyword requiring the user to enter a search query matching the start of col1. 
Splitting col1 from both tables into keywords and put the distinct keywords in a sperate table and add two junction tables joining table1 and table2 to the keyword table.