MongoDB case insensitive query - limit returned fields

Posting to Dreamfactory /api/v2/mongodb/_table/friends?method=GET
works perfect
Performs a case insensitve query where Name like mart or GpPartner like Mend

How can i limit the returned fields, for example i only would like to get _id and Name as Result ?

{
“filter”: {
“$or”: [
{
“Name”: {
“$regex”: “mart”,
“$options”: “i”
}
},
{
“GpPartner”: {
“$regex”: “Mend”,
“$options”: “i”
}
}
]
}

}