VS2008 Query - Modify Code To Search For Items Containing Specified Characters

SELECT ContactID, FirstName, LastName, Male, Female, Email, Address
FROM Contact
WHERE (FirstName LIKE @FirstName + '%')

The above query works and returns values on first names that begin with whatever item I type in a text box.

How can I modify that code to search for items containing specified characters instead of just searching for items that begin with the specified characters. I would still need to use a wildcard because it is a search field. see below for an example

For example can I query the FirstName column to display people who's name contain the letters "an" in that order a before n but anywhere within the word e.g.

- Anna
- Jane
- Samantha