How to _suggest on multiple fields?

To spell check / suggest one single field, we can do as follows:

curl -XPOST localhost:9200/index/type/_suggest -d '{
"field": "MY_FIELD1.suggest",
"term": "wrongly_spelled_word",
"similarity": 0.3 }'

But how do we do the same thing on several fields like MY_FIELD1, MY_FIELD2 etc. I tried

"fields": ["MY_FIELD1.suggest", "MY_FIELD2.suggest"]

etc, but it was not working.