Why not just give them a view into the library that only shows their documents. This way they can still find other documents and you don't have to do anything to the library or have the user's remember to use a custom search string:
Add a Search Results Web part to a page within your site and define the query as such:
(IsDocument:"True" AND CreatedBy={User.Name})
Then add a search Box Web Part and point to the Search Results Web Part. What will happen is when the page is loaded it will show a list of documents that the user has edited. They can then further refine that list by searching in the search box added.
This solution does not require a change to the library or customizing search itself, though it does require adding some web parts to a page on your site.
Hope it helps,
Dave
Author:<their name>
. – Evariste Dec 23 '15 at 8:24