The best solution to leverage, according to me, is to implement Google Site Search. If you already have your site live on the internet, you can test this feature in the below said url. You can get a live preview of search on the site you mention.
Please visit the following link for a quick tour, and resources.
And also note that you for sure have certain tricks that can let you search any website using search engines. For e.g. in google, "site:eggheadcafe.com robbe" searches eggheadcafe for the word robbe.Obviously, your website should be indexed and uptodate by the search engine.
Hope this helps.