How to create/modfiy WP_Query to search in post title OR custom field?

To do an OR search, I tried merging WP_Query results as shown here – Can i merge 2 new WP_Query($variable) ‘s? – in guidod’s answer. That wasn’t a great solution though, and resulted in erratic behaviour.

The correct solution I found was to modify the query using the WP Custom Query as shown in the code (which requires some modifications) here – http://codex.wordpress.org/Custom_Queries ..