docs: function _matchAnyField(fields, matchAnyRegex) {
          var regExp = regExps ? matchAnyRegex ? regExps.any : regExps.all : null;
          if (regExp) {
              var orBuilder = parentBuilder.either();
              for (var i = 0; i < fields.length; ++i) {
                  orBuilder = orBuilder.or().field(fields[i]).is("$regex", regExp);
              }
          }
          return parentBuilder;
      }