Database
[{"_id":"14_0","data":[{"dn":"subdata=data_a","userUL":"0","objectClass":"NEWDATA","userDL":"5"}]},{"_id":"15_0","data":[{"dn":"subdata=data_b","userUL":"0","objectClass":"NEWDATA","userDL":"3"}]},{"_id":"16_0","data":[{"dn":"subdata=data_c","userUL":"0","objectClass":"NEWDATA","userDL":"9"}]}]
Query
db.collection.find({$expr:{$reduce:{input:"$data",initialValue:false,in:{$or:["$$value",{$lte:[{$toDouble:"$$this.userDL"},5]}]}}}})