Could you explain the use case?
Is it a problem with search? Or at index time you want to modify the source document to split content in multiple fields?
It would be easier to provide a recreation script with your source data and a typical search the user would enter.
Just as described in About the Elasticsearch category. It will help to better understand what you are doing. Please, try to keep the example as simple as possible.
A full reproduction script is something anyone can copy and paste in Kibana dev console, click on the run button to reproduce your use case. It will help readers to understand, reproduce and if needed fix your problem. It will also most likely help to get a faster answer.