It sounds like you're using the search box (located at the top right of the main window.) If so, click on the little down arrow to the right of the magnifying glass and select "entire library." Then select "Search Specific Fields" and make sure "Title" is selected plus any other fields you want searched. Lastly take a look at "Search Field Shortcuts." If you have a few search fields set in "Search Specific Fields" you can use "T:SongTitle" and the search will be limited to titles.
One more thing... there's a custom search available from the Edit Menu (in the Menu Bar.) It's called "Find" and give you much more control for searching than simply using the search box.