Advice on geolocation auto fill search from database

All i need is advice on a my data [login to view URL] site is done in php codeigniter.I need advice on how to set a script so when a client looks up a business on grasshopit-dot-com the list is geolocated and autofills so if you look up pizza the nearest pizza business comes up ..If you look up Burger King the nearest burger king come-up from where your doing the search. At this point all i am paying for is advice if you think you can help me with the php script I am willing to pay that also .....