The built-in Drupal search is poor. Search is a hard problem to solve and the best way to solve it is to find someone who has done it well and use their work.
Apache Solr is the popular, blazing fast open source enterprise search platform from the Apache Lucene project. Solr search can be used as a replacement for core content search and boasts both extra features and better performance.
Solr's advantage for Drupal is that it indexes nodes, not pages. This means it can have access to attributes of the node that are not readily parsable from the rendered page. these attributes can be used to filter the results.