Filter ChangeStream events by updates to an array

I’m trying to make a ChangeStream that only triggers on updates to a set of properties in my schema, one of those being an array. I am currently using an $or operator that, for each property I want to check, it adds the filter like this: { "updateDescription.updatedFields.Prop": { $exists: true } } and this works for the majority of cases except when pushing a value to an array or updating it. That’s because the updatedField comes out as prop.X where X is the modified index and I want to match all possible indexes on the query level to reduce the amount of data sent to my app. I’ve searched for a while and couldn’t find any way to use regex against the keys of an object or even the $ operator. Any ideas?