Match part of custom_data component in a predicate

Heya, I have a predicate which should just test for whether {be:1b} exists inside the held item's custom_data component. However, the predicate only runs if the custom_data of the item matches exactly what is specified in the predicate. How do I make it only check if the component includes the data, and not if it matches exactly?
This is the predicate:json {   "condition": "minecraft:entity_properties",   "entity": "this",   "predicate": {     "equipment": {       "mainhand": {         "items": "minecraft:snowball",         "components": {           "minecraft:custom_data": {"be":1}         }       }     }   } }