Gene expression within a cluster across samples

[JerBear2024]

Hi Community,
I'm trying to figure out how to calculate the proportion of cells within a cluster (or subset of clusters) that express gene X (that may or may not be a "marker" gene) above threshold Y (or maybe with at least 2 qualifying variables such as L2FC & padj). I'm ok with the 1st step, which is creating a subset,

NewSubclusterName <- subset(x = SeuratObject, subset = sub_cluster_namedata == "ClusterA" | sub_cluster_namedata == "ClusterB")

but the 2nd part is where I'm at a blank, where I'd like to know how many cells within subset express, say, Mki67 with l2fc >= 1.5 and padj >= 0.001

Any help would be appreciated!