Is there multi master database with customizable replication level?

I need a multi master database to let users talk from different continents. Each user will write his data to his local master database and it will replicate data to other master databases in other counties/continents. The problem is that I can't store all copies of all users data in all data centers. I need something like a database/solution which will let me to set a replication level.
I need to have ability read any data from any nodes but store data on several nodes (on 3 nodes but not on all nodes).

Is there the solution? Maybe a proxy between database and application or a clever cluster? Any ideas or tips will be pleasant