Depending on the size of the site and searching capability needed a more scalable solution may be:
Scan the pages
strip non words/tags
parse the words - create a table with word and page-url as columns
Index on word
Please note you can normalize data if your site is large enough.
your search page can then parse the key words, look up the words individually in the database with a join or a union (depending on type of return you want) as well as searching on partial words.