Information on search engine for a site

[Mr. Akash Gupta]

Attention Content sellers,

Hey!
 anyone of you aware of any good search software which could be placed
on a site to access the site's database depending on the question put up
by the user.The database corresponds to information regarding many people
who are registered members of the site.Depending on the requirements
posted by the user, serch software should be capable of analysing all the
records and finding  appropriate matches .(i.e. records correspondinbg to
different persons which fit the criteria either wholly or most closely.)