How can I select multiple fields when using the documents.get ?

Right now I am getting the documenmt like this:

  const doc = await docs.documents.get({
    documentId: copiedFile.data.id,
    fields: 'body/content'
  });

which returns this:

"data": {
  "body": {
    "content": [...]
  }
}

However, I need to also get the inlineObject and the only way so far I have been able to do so, is by removing the fields proeprty completely

  const doc = await docs.documents.get({
    documentId: copiedFile.data.id,
  });

Then I get this:

"data": {
  "title": "Some document title",
  "body": {
    "content": [...]
  },
  "headers": {
  },
  "footers": {
  },
  "documentStyle": {
  },
  "namedStyles": {
  },
  "lists": {
  },
  "revisionId": "some-long-id",
  "suggestionsViewMode": "SUGGESTIONS_INLINE",
  "inlineObjects": {
  },
  "documentId": "some-long-id"
}

But I am really only interested in data.body.content and data.inlineObjects When selecting everything the response is many thousands of lines of json larger, which I don't want.

I have tried fields: ['body/content', 'inlineObjects'] but that only returns body.content and not the inlineObjects - also the documentation doesn't mention this syntax anywhere, it was just to experiment.