@clients = (
	{ MAC => $mac, RSSI => $rssi, SNR => $snr }, /* 0 */
	{ MAC => $secondmac, RSSI => $secondrssi, SNR => $secondsnr }, /* 1 */
	/* etc */
);

##</code><code>##

%client_0 = %{$clients[0]};

##</code><code>##

my @clients;

# The whole hash at once
$clients[0] = { MAC => $mac, /* ... */ };

# Or setting individual bits
$clients[0]->{MAC} = $mac;