Combining query results in mongodb
From your question, I couldnot clearly understand what is the required business scenario, but with the sample data provided I have given an pseudo code and the respective mongodb implementation of that pseudo code.

if invited field is "0800123456" 
   if event type is 3 and event status is 11
     select matching documents
or if event type is 4 and event status is 11 and primary owner exists
     select matching documents


Mongo DB Query

db.collection.find({
  $or: [
    {
      $and: [
        {
          "invited": "0800123456"
        },
        {
          "eventtype": {
            $eq: "3"
          }
        },
        {
          "eventstatus": {
            $eq: 11
          }
        }
      ]
    },
    {
      $and: [
        {
          "eventtype": {
            $eq: "4"
          }
        },
        {
          "eventstatus": {
            $eq: 11
          }
        },
        {
          primaryowner: {
            $exists: true
          }
        }
      ]
    }
  ]
})


If this is not matching your scenario, then write your own query with the help of this sample code.

Hope it Helps!