If you browse using Google Chrome (and if not, why not?) you can use the browser to search your Google Drive files just as you would use any other search engine.
To get started, right click on the Omnibar (Chrome address bar) and choose Edit Search Engine… from the menu. This opens a settings page for search engines used by Chrome.
Scroll down the engines listed to Other search engines, where you can add a new search engine, and enter e.g. “Google Drive” as the name for your search engine (you can call it whatever you like), and choose a keyword (I’ve used “drv”) as the keyword you’ll type in order to activate search via Google Drive. In the URL field type the following URL:
Now you’re all set. Enter your keyword “drv” in the Chrome omnibar, followed by a space, and you’ll see the term Google Drive appear to the left of the input field. Now you can enter your chosen search terms and search all your Google Drive data.