Most databases will contain conference papers. From your search results choose Document Type or Source Type and limit to Conference Paper or Conference Proceeding depending on the database. Some databases just contain conference papers or have a high proportion of conference papers:
An index to the published literature of the most significant conferences, symposia, seminars, colloquia, workshops, and conventions in a wide range of disciplines, from anthropology to zoology. Conference Proceedings Citation Index, accessed via Web of Science, helps researchers access the published literature from the most significant conferences, symposia, seminars, colloquia, workshops, and conventions worldwide. This resource offers a complete view of conference proceedings and their impact on global research, letting you use cited reference searching to track emerging ideas and new research beyond what is covered in the journal literature. Two editions cover the sciences and social sciences.
An index to the published literature of the most significant conferences, symposia, seminars, colloquia, workshops, and conventions in a wide range of disciplines.
IEEE Xplore provides full text access to the world's highest quality technical literature in electrical engineering, computer science, and electronics. Access is to the full text published since 1988 and select content published since 1913 from: IEEE journals, transactions, proceedings, and magazines; IEEE conference proceedings; IEEE published standards; IEEE Spectrum Magazine; IEEE-Wiley eBooks collection; IET journals; IET conference proceedings.