title: Fetch sub-document Mongodb only match with criteria
body: <p>I have data in mongodb like this:</p>
  
  <pre><code>{
      "_id" : ObjectId("55a12bf6ea1956ef37fe4247"),
      "tempat_lahir" : "Paris",
      "tanggal_lahir" : ISODate("1985-07-10T17:00:00.000Z"),
      "gender" : true,
      "family" : [ 
          {
              "nama" : "Robert Deniro",
              "tempat_lahir" : "Bandung",
              "tanggal_lahir" : ISODate("2015-07-09T17:00:00.000Z"),
              "pekerjaan" : "IRT",
              "hubungan" : "XXX",
              "tanggungan" : false,
              "_id" : ObjectId("55a180f398c9925299cb6e90"),
              "meta" : {
                  "created_at" : ISODate("2015-07-11T20:59:25.242Z"),
                  "created_ip" : "127.0.0.1",
                  "modified_at" : ISODate("2015-07-12T15:54:39.682Z"),
                  "modified_ip" : "127.0.0.1"
              }
          }, 
          {
              "nama" : "Josh Groban",
              "tempat_lahir" : "Jakarta",
              "tanggal_lahir" : ISODate("2015-06-30T17:00:00.000Z"),
              "pekerjaan" : "Balita",
              "hubungan" : "Lain-Lain",
              "tanggungan" : true,
              "_id" : ObjectId("55a29293c65b144716ca65b2"),
              "meta" : {
                  "created_at" : ISODate("2015-07-12T16:15:15.675Z"),
                  "created_ip" : "127.0.0.1"
              }
          }
      ]
  }
  </code></pre>
  
  <p>when i try to find data in sub-document, with this code:</p>
  
  <pre><code>person.findOne({ _id: req.params.person, {'family.nama': new RegExp('robert', 'gi') }}, function(err, data){
    // render code here
  });
  </code></pre>
  
  <p>It show all data in Family Data,
  Can we fetch or display a data only match with criteria/keyword, for example only "Robert Deniro" row</p>
  
  <p>Thank You</p>