Daylite offers you a global search in the upper right corner which allows you to search for data records in Daylite. Here you can also search for an email address, postal address or phone number to find the corresponding record.
Daylite gives you the following data types via the search:
It is not possible to search for a category or a keyword. However, you can create a filter list for this purpose. How this works is described in the following article: How do I create a smart list?