Thread:Project:Support desk/search function does NOT include similar characters like "á" and "a"/reply (4)

Yes, the default MW search engine is notoriously limited I'm afraid. Another oversight in search results occurs when a word is preceded by a quotation mark. For any extra functionality, you might be able to do two things:
 * (1) Install a search engine such as Lucene or Sphinx, as Subfader already suggested, and an appropriate MW extension (for a list see my user page). Unfortunately, this may not be an option for the average user, because it requires shell access. If you're on a shared host, you're probably out of luck, but contacting your hosting company can do no harm.
 * (2) use an external search engine such as Google. One serious downside to this strategy is that it may be slow on updates.

See also http://www.mediawiki.org/wiki/Search (though it rather shows how much things have remained still).

Of course, you can always redirect "Ernesto Fama" to "Ernesto Famá".