First enable the DB Search API Module.
Goto /admin/config/search/search-api – Search API config page.
Click Add Server, Give it a name where Backend will be Database
Once again go to Search API config page and click Add Index.
Give it a name, select a datasource(for eg Content) from which index is to be made and select the Server as the one we created and click Save.
Edit the Index and click the Add Fields Tab and fields to be indexed.
Add the necessary fields, Change the type in the Edit Page from String to Fulltext to get partial search for the Title and give boost number to give the field more prominence while searching
Click the View Tab and click Index now.