Can a man marry step sister of his wife. i.e such sister who has the same mother but different father
First of all you must understand is Islam doesn't differentiate between half-siblings. A sibling is a sibling.
Also there are rules about qualifying half siblings who were nursed by your mother or you parents took them in and called them their children. These rules I don't know in detail. But there is almost no differentiation between Siblings and Half Siblings and there is NO differentiation between the two when it comes to Nikkah.
Now there are these Ayats of Quran: [4:22-24] An-Nisa
And do not marry the women who were wedded to your fathers (and grand fathers), except what has already passed; that is indeed an act of shame and great wrong; and an evil way.
Forbidden for you are your mothers, and your daughters, and your sisters, and your father’s sisters, and your mother’s sisters, and your brothers’ daughters and your sisters’ daughters, and your foster-mothers (who breast-fed you), and their daughters (your foster-sisters), and your wives’ mothers (mothers-in-law), and your wives’ daughters who are under your protection - born of the women with whom you have cohabited; and if you have not cohabited with them, then it is no sin for you to marry their daughters; and (forbidden are) the wives of your own sons (and foster-sons and grandsons) and the keeping of two sisters together in marriage, except what has already passed; indeed Allah is Oft Forgiving, Most Merciful.
And all married women are forbidden for you except the wives of disbelievers who come into your possession as bondwomen; this is Allah’s decree for you; and other than these, all women are lawful for you so that you seek them in exchange of your wealth in proper wedlock, not adultery; therefore give the women you wish to marry, their appointed bridal money; and after the appointment (of bridal money) there is no sin on you if you come to a mutual agreement; indeed Allah is All Knowing, Wise.
According to my knowledge the rules for slave girls was later amended by Hadith.. I can not refer to Hadiths about this but this is the accepted rule by scholars.
After this then there is the rule if one can marry sister of a Wife after the wife has passed away or divorced. That case is "Yes" but ask scholars.