Advance Site search

Looking for a experienced PHP, MySQL, Javascript Developer to code a advanced site search. The search engine for the site needs to be a standalone application/plugin very flexible and structured. Using PHP and PDO with vanilla Javascript no framework Jquery etc. results via ajax and ability to allow/disallow search between Tables, Records, and Fields in the database. Some features that it should possess. 1. Autocomplete 2. Ability to search within a particular department/categories 3. Flexible search parameters 4. Accurate/Quality search results and relevant to the user's query 5. Avoid zero results by using autocomplete or rather than showing no results at all, serve up results that are related to the search term. 6. Handle misspellings 7. Intuitive Customer Expression and Smart Search Suggestions (See below for details) Would like suggestion or improvement from hired developer. The site search should be smart enough to recognize "pants," "slacks," and "trousers" as the same kind of product. Recognize spelling mistakes and auto-suggest alternatives in real time. Dynamically create such connections, rather than rely on constant manual updates from a programmer. please note budget is negotiable.