what would you call this chord?

D

A

F

G

to my ears it's an embellished Dm

(an added 4; as opposed to "sustained" (substituting the 3)

so would that be called a Dmadd4?

or 

Dm/G?

or?

Context:

I came across on in a tut of "Lean on Me," using guitar to mimick the piano chords)

the guy doesn't name this chord;

but he says it's resolving the G6 before it;

but to my ears that's just an Em/G;

because there's no D in it

G

E

B

G

G

as I say that...

it might sense to me that it's sort of descending from Em, to Dm; over G (fifth of C)

so it's like it's pulling slowly down to the Tonic; but with all the tension of that Dominant pitch

i guess that's why it has so much longing in it?

anyways...

thoughts?

That's all just an extended harmony G (V) chord.  You've got the right idea thinking of it as piano chords adapted to guitar.  Guitarists typically look at & think of everything as a frozen, isolated vertical shape.  So, you could think of it as Em/G to Dm/G.  But the chords in that song are better thought of as triad voicings moving over the G bass note.

This matches the vocal harmony at the end of the line that sings an E down to a D.  So if you harmonize that using the C major scale you happen to get an E minor chord to D minor chord with a G in the bass.  But it's easier to think of it as all just a G chord with color tones.

|------------------------|
|--5-(6)-----3-(5)-------|
|--4-(M3)---2-(9)-------|
|--5-(1)-----3-(m7)-----|
|------------------------|
|--3-(1)-----3-(1)-------|

So, a G6 to a G9(no3rd).

The original piano part also moves down one more triad voicing to include what results in a G11.

|-------------------------------|
|--5-(6)-----3-(5)----1-(11)---|
|--4-(M3)---2-(9)----2-(9)----|
|--5-(1)-----3-(m7)--3-(m7)--|
|-------------------------------|
|--3-(1)-----3-(1)----3-(1)----|

G6 to G9(no3rd) to G11(no3rd).

If I was playing it with a band I'd just let the bass and, or piano play the low G & I would only play the upper descending triads.  Kind of like just playing the right hand part of the piano.  If I was playing it on solo guitar, then I'd try to add the low G on some of the chords.

Fun question!  Hope that helps!