Jquery validate depend field

I have 4 fields where the user should enter values in at least one of them. So I am trying to validate that each of these 4 fields will be required just when all of them are empty otherwise it won't be required.

The rule seems to be working for the one field I picked to try first, but the required error remains even after I provide a value.

This is my code:

$("#ProspectDtlFrm").validate({
  rules: { 
    prsptEmail: {
      required: function(element) {
        return (
          $("#prsptHomePhone").val() == '' &&
          $("#prsptBusinessPhone").val() == '' &&
          $("#prsptMobilePhone").val() ==''
        ) 
      }                                         
    }    
  },
  messages: {
    prsptEmail: "Please enter your first name"
  }
});