Notepad gives you two search options.

Easy Search will match any text you entered in the search field even in a not contiguos way, for example “nice girl” will match “Mary is a nice girl” as well as “Berenice is a little girl“.

Regular Expression is an advanced search method based on patterns, for example “nice|girl” will match either “nice try” and “pretty girl“. More info on it can be found on many websites such as the dedicated page of the Wikipedia.