@truekasun there is no way to do that with the Content API.
If you want to allow users to search then can be done through a dedicated search service like Algolia and Google Custom Search, or via client-side approaches like Ghosthunter. There are more ideas in the related Ideas topic:
@Kevin, I just want to implement the search function on my Android app. So Ghosthunter will not be a solution. Probably I will be able to do something with Algolia or even better with ElasticSeach.