I have documents like this:

```
    {
      _id: 'some id',
      body: 'i want some apple',
    },

    {
      _id: 'some id2',
      body: 'i want some apple and banana',
    }

```

And i want to find and replace all of document's body phrase `some apple` to `lots of oranges`.

Expected Results:

```
    {
      _id: 'some id',
      body: 'i want lots of oranges',
    },

    {
      _id: 'some id2',
      body: 'i want lots of oranges and banana',
    }

```

So i find all the documents with this:

```
    myDB.find({
        "body": {
          "$regex": "some apple",
          "$options": "i"
        }
      },
      function(err, docs) {
        console.log(docs);
      }
    );
)

```

But don't know how to replace and update only document's specific body phrase `some apple` to `lots of oranges`. 

How do i do this?