Many Web sources provide forms to allow users to query their hidden data. For instance, online stores such as Amazon.com have search interfaces, using which users can query information about books by providing conditions on attributes of title, author, and publisher. We propose a novel system framework that supports keyword queries on structured data behind such limited search forms. It provides user-friendly query interfaces for users to type in IR-style keyword queries to find relevant records. We study research challenges in the framework and conduct extensive experiments on real datasets to show the practicality of our framework and evaluate different algorithms.