Blogger Pierre Igot (www.betalogue.com) was frustrated with the search behaviour in Lion’s Safari. In Snow Leopard’s Safari, if you pressed Cmd-F (or selected Edit > Find) and then entered a string of text, the program would find any instance of that text in the current web page – whether it was a whole word or just part of one. Unfortunately, in Lion’s Safari, search doesn’t work that way: it matches strings that are whole words or that appear at the beginnings of words, but it doesn’t find them within words.
Fortunately, some of Pierre’s readers came up with the solution. As it turns out, Safari in Lion offers finer-grained controls for setting the search scope. Once you’ve pressed Cmd-F to initiate a search, you can click the magnifying glass within the search box to expose a small menu. From the menu, you can choose between Contains or Starts With.
Starts With, the default option, matches substrings only when (as the name suggests) they start words (that includes cases in which the string matches the entire word). The Contains option does what the name implies, thus giving you the functionality you had in Snow Leopard. It finds substrings regardless of where they occur in a word.
Make Contains the default option by opening Terminal and entering defaults write com.apple.Safari FindOnPageMatchesWordStartsOnly -bool FALSE, pressing Return, and then relaunching Safari.