Nested Query on arbitrary fields

gistfile1.sh

# The documents that're index all have an arbitrary nested field, named "message", "post", and "content", respectively.
# Can a nested query be built to search all of the nested fields without specifically referencing each nested field?

curl -s -XDELETE localhost:9200/test 2>&1 >/dev/null
curl -s -XPUT localhost:9200/test >/dev/null

curl -XPUT localhost:9200/test/tweet/_mapping -d '
{
 "tweet" : {
   "properties" : {
     "name" : {
       "type" : "string"
     },
     "comments" : {
       "properties" : {
         "message" : {
           "type" : "string"
         },
         "username" : {
           "type" : "string"
         }
       },
       "type" : "nested"
     }
   }
 }
}
'

echo
curl -XPUT localhost:9200/test/tweet/1 -d '{
 "name"     : "Jane",
 "comments" : [ {"message" : "this is text", "username" : "Jane"} ]
}'

echo
curl -XPUT localhost:9200/test/tweet/2 -d '{
 "name"     : "Jack",
 "comments" : [ {"post" : "this is text", "username" : "Jack"} ]
}'

echo
curl -XPUT localhost:9200/test/tweet/3 -d '{
 "name"     : "Jack",
 "comments" : [ {"content" : "stuff here", "username" : "Jack"} ]
}'

echo
curl localhost:9200/test/_search?pretty=true -d '
{
  "query": {
    "nested": {
      "path": "comments",
      "query": {
        "bool": {
          "must": [ { "text": { "comments.text": "this" } } ]
        }
      }
    }
  }
}
'