There is no one database that provides comprehensive coverage on a topic. It is wise to try the MLA, but then there is also Academic Search Complete (with Literature Databases,) JSTOR, and others. Each database has its own specific coverage and subscriptions to individual journals. When in doubt, check under Subject and Research Guides in Language and Literature for selected databases to use.
The Modern Language Association International Bibliography database is available on library subscription. There are Basic (keyword only) and Advanced Search options available (see Help here).
Use Thesaurus, Names as Subjects, Cited References, and Indexes --- all visible in the bar at the top of the search screen ---for focused and comprehensive searches.