Create searchable database for website designed on php

Hi, I have an existing website on the php platform. I would like to create a searchable database for FAQ/Troubleshooting for my software product. The search should have an autocomplete function. Also, previously searched phrases should show up automatically. For example, if a user has entered a search term "product roadmap" previously, the next time another user enters the word "product" the search should suggest "product roadmap" to the user The speed of the search should be instantaneous.