How to search in Apache Solr multiple indexes at once?

Question

Solr

Good afternoon, I have Apache Solr 7.5
For example, it has 3 cores / indexes: EMPLOYEES, DOCUMENTS, NEWS
All 3 cores are successfully indexed and are perfectly searched, and now the task has arisen,
but how to make it so that the search can be done once for all
Roughly speaking, ANDREY entered the indexes, in my results I have employees with the name Andrey, and a document in the title of which is Andrey, and the news in the text of which is Andrey.
(all entries in the indexes have no connection with each other)

Answer 1

Combine all 3 results - not fate?

Answer 2

all entries in the indexes have no connection with each other

Only software.