You can search the titles, artists, albums, and composers of songs, podcasts, and other content you’ve synced to iPhone.
Enter text in the search field at the top of a song list, playlist, artist list, or other view of your iPod content. (Tap the status bar to scroll quickly to the top of a list and reveal the search field.)
Search results appear automatically as you type. Tap Search to dismiss the keyboard and see more of the results.
You can also use Spotlight to search for music. See Searching.